Stacey Burrows, who runs Articulate, was approached by producers last autumn.

“They asked if I’d work with the child cast, helping them with diction and clarity in their speech. I jumped at the opportunity to be involved,” she said.

“It’s about the adventures of a young boy, Hank, based on Henry’s experiences of growing up with dyslexia.

" Although it’s set in London, it was filmed at a school in Halifax.

"I worked on an intense five-week shoot and the energy on set was fantastic, even more so when Henry, who plays super-cool music teacher Mr Rock, was there.

“Henry has time for everyone; one day he was chatting to local children who were extras. He’d brought them all a Hank Zipzer book and was writing personal messages in them. The children were delighted.”

Best known as The Fonz in American 1970s TV show Happy Days, Mr Winkler visited Bradford in 2011 to talk to schoolchildren about dyslexia.

He brought his My Way tour, raising awareness of learning difficulties, to the Abundant Life Centre and told the Telegraph & Argus he was not diagnosed with dyslexia until he was an adult.

“My son was doing a school report on Native Americans and couldn't stop talking about it – but he could only write three sentences. We had him tested and I thought ‘Oh my God, that's me’,” said the actor.

“When I was a child in New York nobody knew about learning difficulties. My parents called me ‘dumb dog’ and said I was lazy. I studied hard but I didn't know what I was reading.

“One in five children has a learning difficulty. If people around them have a greater understanding of it they can give them the support they need.